Method of forming brake drums



March 2 939- c. w. SINCLAIR METHOD OF FORMING BRAKE DRUMS Filed Sept.14, 1936 FIG.

R mm mm NS w s E L R A H c I A rromws 12s FIG.5.

Patented Mar. 21, 1939 UNITED STATES PATENT ()FFI METHOD OF FORMINGBRAKE DRUMS Application September 14, 1936, Serial No. 100,784

7 Claims.

The invention relates to the manufacture of brake drums and refers moreparticularly to the manufacture of composite brake drums.

One of the objects of the invention is to pro- 5 vide an improved brakedrum constructed to be of relatively light weight and at the same timemaking provision for the heat generated by the application of the brake.Another object of the invention is to manufacture the brake drum by animproved and economical method whereby a material saving in metal iseffected and at the same time a strong, substantial construction ofbrake drum is produced.

These and other objects of the invention will become apparent from thefollowing description, taken in connection with the accompanyingdrawing, in which Figure 1 is a plan view of a blank used in themanufacture of the brake drum;

20 Figure 2 is an end view of the blank of Figure 1;

Figures 3 and 4 are elevations illustrating different steps in themethod;

Figure 5 is a section illustrating another step in the method;

Figure 6 is a section illustrating the completed brake drum.

In general, I start with strip stock having a longitudinally extendingportion of substantially uniform gauge and an adjacent longitudinallyextending portion of a gauge decreasing in a direction from the firstmentioned portion. This stock is hooped and its ends are weldedtogether, after which the portion of varying gauge is contracted. Duringthe contraction the metal is upset to a gauge not greater and preferablyless than that of the first mentioned portion. Then a web is secured tothe free end of the contracted portion to complete the brake drum. Byreason of forming the brake drum in this manner, the portion ofsubstantially uniform gauge is at least as thick and preferably thicker.than the remaining portion. Its gauge is suificient to form asufficiently heavy body which may be used as the brake engaging portionand which will serve to store and distribute and dissipate the heatgenerated by the application of the brake. By reason of the contractedportion, the size of the web, which may be a fixed flange upon a hub, isreduced to thereby reduce the total weight. The reduction of the totalweight is also effected by starting with a blank having a portion oftapered section.

In carrying out my method, I start with the sheet metal blank I,illustrated in Figure 1. This blank is formed from strip stock andissymmetrical with respect to its longitudinal median axis. As shown, ithas the edge portions 2 of substantially uniform gauge and the middleportion 3 of a varying gauge, this middle portion decreasing in gaugefrom the edge portions to the longitudinal median axis of the blank. Theblank I is cut to length, after which it is hooped, its ends are Weldedtogether and the weld flash is removed to form the annular member l,illus trated in Figure 3.

The blank I may be severed along its longitudinal median axis 1', eitherbefore forming the annular member 4 or after this annular member isformed. In either case, each of the resulting blanks may be flanged atone end to provide the annular flanged member 5, illustrated in Figure4, the flange 5 extending radially outward- 1y at the free end of theedge portion of substantially uniform gauge.

The annular flanged member 5 is then operated upon by the die 6, whichcomprises the female die member I and the male die member 8, whichcooperate to contract the portion 3 of varying gauge, which portiondecreases progressively from the portion 2 of substantially uniformgauge. These die members form the tapered portion 9 having at its freeend the approximately cylindrical part it. During the contraction, themetal which forms the tapered portion 9 is upset to a gauge preferablyless and, in any event, not greater than that of the portion ofsubstantially uniform gauge.

After the forming of the annular member 5, the web II is located withinthe approximately cylindrical part iii and fixedly secured thereto. Thisweb ll may be formed of sheet metal and welded in place and adapted tobe secured to a wheel hub. Figure 6 illustrates the completedbrake'drum.

With this method, it will be seen that a strong, substantialconstruction of brake drum is secured having a brake flange which isformed from the edge portion 2 of the blank and which is of sufficientbody to take care of the heat generated by the application of the brake.It will also be seen that by reason of the tapered portion 9, which isformed from the portion 3 cf the blank of varying gauge, the totalweight of the brake drum is reduced, both by reason of the portion 3being of less gauge and by reason of the decrease in diameter of theweb. Furthermore, the construction is such that the brake flange isproperly axially offset with respect to the Web.

What I claim as my invention is:

1. The method of forming a sheet metal brake drum, comprising providinga sheet metal tubular blank having an annular brake engaging portion andan annular portion decreasing in gauge from the brake engaging portion,contracting the last mentioned portion and thereby upsetting the metalthereof, during the contracting forming a tapered part and anapproximately cylindrical part at the free end of the tapered part, andthen securing a web to the approximately cylindrical part.

2. Those steps in the method of forming a brake drum which consist informing a substantially flat strip of stock with a longitudinal edgeportion of substantially uniform gauge and with the oppositelongitudinal edge portion varying in gauge from the first portion,fashioning the strip of stock to form a tubular blank, contracting theportion of the tubular blank of varying gauge in a manner toprogressively upset the material thereof to form a radially inwardlyinclined section provided with a reduced substantially cylindricalportion, and securing a web to the cylindrical portion.

3. Those steps in the method of forming a brake drum which consist informing a tubular blank with an annular brake flange engaging portionand with an annular portion decreasing in gauge from the brake engagingportion, and upsetting the material of the annular portion of decreasinggauge by contracting said annular portion.

4. Those steps in the method of forming a brake drum which consist infashioning a tubular blank from a strip of stock having a portion of onelongitudinal edge progressively decreasing in gauge from thelongitudinal center line of the strip of stock, and upsetting theannular portion of the tubular blank of progressively decreasing gaugeby contracting said last named portion.

5. Those steps in the method of forming a brake drum which consist infashioning a tubular blank from a strip of stock having the oppositelongitudinal edge portions respectively of substantially uniform andvarying gauge, and contracting the annular portion of the tubular blankof varying gauge to upset the material in the latter portion to a gaugenot greater than the substantially uniform gauge of the first namedportion.

6. Those steps in the method of forming a brake drum which consist inproviding a strip of stock having a portion of one longitudinal edge ofuniform gauge and having the portion at the opposite edge decreasing ingauge from the portion of uniform gauge, hooping the strip of stock toform a tubular blank, and progressively contracting the portion of thetubular blank of varying gauge in a manner to progressively upset thematerial thereof.

'7. Those steps in the method of forming a brake drum which consist informing a tubular blank from a strip of stock having a portion of onelongitudinal edge of substantially uniform auge and having the portionof the opposite edge decreasing in gauge from the portion of uniformgauge, contracting the portion of the blank of varying gauge, andsecuring a mounting member to the contracted portion.

CHARLES W. SINCLAIR.

